DESCRIPTION: The application is concerned with the mechanisms of sensory - transduction by chemosensory neurons of the vomeronasal organ (VNO). A series of patch-clamp recording experiments are proposed to characterize the voltage-gated ionic currents in dissociated mouse vomeronasal neurons, and to determine if second messenger-gated ion channels are present in these cells. Retrograde labeling of VNO neurons in vivo prior to dissociation, or antibody labeling for cell specific markers in fixed, dissociated cells, will be used to confirm visual identification of dissociated chemosensory VNO neurons from which recordings will be obtained. Whole cell patch recordings in voltage clamp mode will be used to analyze Na+, Ca++, and K+ currents in terms of which ion carries them, their I/V functions, their inactivation kinetics and their pharmacology. In other experiments, three approaches (excised patch recordings, intracellular dialysis, and application of membrane permanent analogs) will be used to test whether cAMP, cGMP, or IP3-gated channels are present in these cells.